Car seat base



FIG. 1 is a front perspective view of a car seat base, showing my new design.

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is an overhead plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The features shown in broken lines are for illustrative purposes only and do not form part of the claimed design. 

The ornamental design for a car seat base, as shown and described. 